The Thing in Itself in the Light of a Mirror

Everybody talks about the objective fact or thing in itself all the time; the thing that exists distinctly from and independent of perception. In response, I would like to consider two people looking at a mirror in which each sees the other's reflection. Both looking at the same object which reflects two entirely separate visual realities simultaneously. We could add two more people gazing at the mirror and we have two more entirely separate visual realities in the one object. Or an infinite number of possible points of perspective, each resulting in a distinct visual reality in the entity of the mirror. So which is the mirror in itself? Are there an infinite number of mirrors and separate realities existing simultaneously or is there one mirror which is a "thing in itself"? If we are to believe in the thing in itself as an objectice reality then we seem to be forced to separate this thing's existence from the visual field, and likewise we would seem to have to separate our perception from any contact with reality. Reality retreating from all known experience of it into some kind of idealised realm beyond our perception. Which would seem to be forming a philosophy to justify a pre-conception, ie that external reality is an objective fact. This possibly explains the desire behind Plato's bizarre world of ideal forms; an escape route from undesired and unsettling implications arising from perception.